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Lesson

Magnesium: Three Field Uses

12 min Meds & Pharma Skip to quiz

Objective: Keep magnesium’s three uses separate: eclampsia, torsades, and severe asthma. It can stop breathing. It is not a harmless mineral. The card has the amount and the rate.

Why this matters

Magnesium has three field uses. Keep them separate: eclampsia, torsades, and severe asthma. It is not a harmless mineral. It can stop the drive to breathe.

Do not give an eclampsia infusion as a fast push. That can drop the blood pressure and stop breathing. The card has the amount and the rate.

Magnesium may be considered for polymorphic VT with a long QT. That is torsades. Routine magnesium is not recommended for polymorphic VT with a normal QT. Magnesium during arrest does not improve outcomes as a general antiarrhythmic. You do not have a serum magnesium level. Watch the patient.

Key points
  • Name the job before you open the vial: eclamptic seizure, long-QT torsades, or severe asthma per protocol.
  • Eclampsia is an infusion, or intramuscular if there is no IV. It is not a fast push. Have a bag-valve mask. Magnesium can stop the drive to breathe.
  • You do not have a serum magnesium level. Watch the patient, not a lab you cannot draw.
Verbalize
  • Which of the three jobs is this: eclampsia, torsades, or severe asthma?
  • Eclampsia: magnesium first, not a benzodiazepine first.
  • Torsades: unsynchronized shock if pulseless or unstable. Magnesium if it is the long-QT polymorphic picture.
  • Watch the drive to breathe. Have a bag-valve mask.

Clinical sequence

  1. Name which of the three jobs this is. Eclampsia, torsades, or severe asthma. Do not open the vial until you can say it.
  2. Eclampsia: magnesium first, not a benzodiazepine first. This is an infusion, or intramuscular if you have no IV. It is not a two-second push.
  3. Torsades: unsynchronized shock if the patient is pulseless or unstable. Magnesium does not replace electricity. Magnesium fits the long-QT polymorphic picture, not every wide complex.
  4. Watch the drive to breathe. Have a bag-valve mask. Label the bag. Your protocol sets the amount and the rate.

1. Eclampsia

Magnesium is first-line for a presumed eclamptic seizure, in pregnancy or up to 6 weeks after delivery. Give an IV loading infusion. Use a split intramuscular dose if there is no IV. See eclampsia. This is not a 2-second push. The card has the amount and the rate.

2. Torsades de pointes

  • Polymorphic VT with a long QT is the magnesium indication.
  • Pulseless or unstable: defibrillate. The shock is unsynchronized. Magnesium does not replace electricity.
  • Polymorphic VT with a normal QT, often ischemic, is not a magnesium problem. Treat ischemia and follow the protocol antiarrhythmic.

3. Severe asthma

Magnesium is an add-on in some protocols after bronchodilators, for life-threatening bronchospasm. It does not replace albuterol, oxygen, or an airway plan. In most teaching pathways it is an infusion, not a fast push. The card has the amount and the rate.

Toxicity

  • Loss of reflexes, slow or stopped breathing, low blood pressure, then arrest. This is a known pattern when an obstetric dose is wrong.
  • If a pregnant patient arrests while a magnesium infusion is running, stop the magnesium and give calcium.
  • This site does not list amounts or rates. Your protocol sets the mix. Label the bag.

Common errors

  • Magnesium for every wide-complex tachycardia.
  • Pushing an eclampsia dose the way you push adenosine.
  • No bag-valve mask ready.

Practice

One-minute check

A partner names three patients: a postpartum seizure; pulseless polymorphic VT; a talking patient with moderate asthma. For each, say magnesium yes or no, and shock yes or no.

Related: Eclampsia, Wide-complex tachycardia, Albuterol.

Sources & Further Study

Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.

Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.

Check Your Understanding

Questions drawn only from this lesson. After you check, the key is highlighted. Education practice — not a certification exam.

1. The three EMS magnesium jobs in this lesson are:
2. Pulseless torsades is treated first with:
3. For polymorphic VT with a normal QT, routine magnesium is:
4. If a pregnant patient arrests while receiving IV magnesium:
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